xlsx-author

xlsx-author is a skill for Claude Code from anthropics/financial-services. It costs 32 tokens per session (461 once invoked), scanned A, original, Apache-2.0.

A way to create an Excel workbook file when no live Excel application is open. It places inputs, formulas, links, and checks into a structured .xlsx file saved on disk.

In plain words
What is it for?
Use it to build financial models, reports, and calculation workbooks in headless environments—sessions running without a graphical Office app. The output is an Excel file in an output folder.
Why use it?
It lets an automated coding session deliver a usable workbook without controlling a desktop spreadsheet program. Clear input and formula conventions also make the calculations easier to review.

Skill for Claude Code ✓ vendor

Written for Claude Code: shipped in a Claude Code plugin.

Part of the earnings-reviewer plugin — 6 skills, 1 agent shipped together

Good fit Use it to build financial models, reports, and calculation workbooks in headless environments—sessions running without a graphical Office app. The output is an Excel file in an output folder.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/anthropics/financial-services/xlsx-author
About the project

Claude for Financial Services is a collection of agents, skills, commands, plugins, and data connectors for investment banking, equity research, private equity, and wealth-management workflows. Financial professionals use it to draft models, memos, research notes, and reconciliations for review by qualified people. The catalogue contains components from these workflows, including agents, skills, plugins, commands, and instructions.

anthropics/financial-services · 34,762 stars · on GitHub

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add anthropics/financial-services --skill xlsx-author
Clone the repo
git clone --depth 1 https://github.com/anthropics/financial-services

Made for: Claude Code.

Or install earnings-reviewer, the plugin that ships this one along with the rest of its 6 skills, 1 agent.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for xlsx-author

README.md
[![agentmods](https://agentmods.dev/badge/skills/anthropics/financial-services/xlsx-author/github.svg)](https://agentmods.dev/skills/anthropics/financial-services/xlsx-author)
Your own site
<a href="https://agentmods.dev/skills/anthropics/financial-services/xlsx-author"><img src="https://agentmods.dev/badge/skills/anthropics/financial-services/xlsx-author/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for xlsx-author

Your own site · 80×15
<a href="https://agentmods.dev/skills/anthropics/financial-services/xlsx-author"><img src="https://agentmods.dev/badge/skills/anthropics/financial-services/xlsx-author.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 32 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 461 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • Socket pass 8 May 2026
  • Snyk pass 8 May 2026
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00032 $0.00461
Opus 5 $0.00016 $0.00230
Sonnet 5 $0.00006 $0.00092
Haiku 4.5 $0.00003 $0.00046

Measured 10d ago against content hash 85b5b76901a7, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

xlsx-author scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 10d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

Copies of this mod

1 near-identical copy found in the catalogue:

plugins/agent-plugins/earnings-reviewer/skills/xlsx-author/SKILL.md · 43 lines

What it actually says

xlsx-author

Use this skill when running headless (managed-agent / CMA mode) and you need to deliver an Excel workbook as a file artifact rather than editing a live workbook via mcp__office__excel_*.

Output contract

  • Write to ./out/<name>.xlsx. Create ./out/ if it does not exist.
  • Return the relative path in your final message so the orchestration layer can collect it.

How to build the workbook

Write a short Python script and run it with Bash. Use openpyxl:

from openpyxl import Workbook
from openpyxl.styles import Font, PatternFill

wb = Workbook()
ws = wb.active; ws.title = "Inputs"
ws["B2"] = "Revenue"; ws["C2"] = 1_250_000_000
ws["C2"].font = Font(color="0000FF")           # blue = hardcoded input
calc = wb.create_sheet("DCF")
calc["C5"] = "=Inputs!C2*(1+Inputs!C3)"        # black = formula
wb.save("./out/model.xlsx")

Conventions (mirror audit-xls)

  • Blue / black / green. Blue = hardcoded input, black = formula, green = link to another sheet/file.
  • No hardcodes in calc cells. Every calculation cell is a formula; every input lives on an Inputs tab.
  • Named ranges for any value referenced from a deck or memo.
  • Balance checks. Include a Checks tab that ties (BS balances, CF ties to cash, etc.) and surfaces TRUE/FALSE.
  • One model per file. Do not append to an existing workbook unless explicitly asked.

When NOT to use

If mcp__office__excel_* tools are available (Cowork plugin mode), use those instead — they drive the user's live workbook with review checkpoints. This skill is the file-producing fallback for headless runs.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 10d ago First seen · 43 lines · 32 tokens per session scan A 85b5b76901a7

Subscribe to this mod's changes

xlsx-author is a skill published in the GitHub repository anthropics/financial-services (34,762 stars, last pushed 15d ago), licensed Apache-2.0. It adds 32 tokens to every session and 461 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.